Each year, between 400,000 and 500,000 premature babies are born. Of these, some 10% will develop respiratory distress syndrome requiring supplemental oxygen therapy. It is, at present, unknown what percentage of this latter group will develop serious retrolental fibroplasia. The principal investigators are conducting a survey in the Premature Intensive Care facility at Jackson Memorial Hospital to identify all cases of retrolental fibroplasia developing among prematures treated at this facility. In addition, fundus photography and fluorescein angiography are performed on babies where appropriate. Pathological correlations are made on post mortem specimens obtained from infants who have expired in the nursery. An ongoing statistical survey of the factor or factors which seem to be influencing the course of the disease is being conducted as well.